Network Issues could also be the reason why your emails are stuck in the Outbox. High ping or data loss can also interfere with the functionality of Outlook.

Network Issues: Issues related to your ISP, router, firewall, DNS settings, Proxy settings, VPNs and more could cause issues with your network.

This means that if you are trying to send a file larger than its permitted size then unfortunately Outlook won’t be able to handle this issue and your email will be stuck in the outbox. But some email providers limit the size of attachments in an email.

Large Attachments: Email attachments have been a thing for a long time and the ability to send files has been a much welcome addition.

Here are a few common reasons why users end up facing this issue in Outlook. It could be network issues, incorrect internet setup on your device, proxies, VPNs, and a lot more.

Your emails could be stuck in the outbox due to a various number of factors. 15 ways to fix the emails stuck issue in Outlook.10 ways to check for issues with Outlook app.

Outlook stuck in offline mode 2016